I believe he believes that he rushed it so he is trying to take a step back. However, I may be wrong.
Basically, the book investigated how long it usually takes a couple to kiss and or do the naughty. He is surprised it takes that long
He's ashamed that it took him 10 years while everyone else took 4 to 6 months
They just became official "lovers". He read the book and thought he had to wait 6 more months in order to do it.
Can someone explain what the last panel meant?